Solar air heating systems are known in the art. Such systems are typically mounted to the exterior of a building, either over its walls or on its roof, and can be used to heat ventilated fresh air brought into the building, or alternatively can be used to heat recirculated air. Heat energy enters the system via a collector and is transported through a plenum which is at a lower pressure than the surrounding air.
Conventional active solar air conditioning systems for heating or cooling using a modular collector typically fall into one of two categories—glazed and unglazed systems. Glazed collectors are typically closed loop systems wherein the air to be heated is closed within the space it is heating and this same air is recycled through the collector. Glazed collectors are typically designed for space heating and cooling applications and are comprised of an exterior glazing and an internal absorber plate. The absorber plate is provided in direct contact with a recycled fluid such as air or water, and the whole is contained within a single assembly usually no more than 3.0 m2 in size. Such collectors have operating efficiencies typically in the range of 30-50% and are typically designed for residential applications due to the limited amount of total air volume that may be delivered by them.
Unglazed systems are typically categorized as either transpired or backpass collectors. Transpired collectors generally consist of a dark exterior absorber with small holes spaced uniformly across its surface. As sunlight strikes the dark surface it absorbs the heat and conducts it from the surface. An approximately 1 mm thick thermal boundary layer of air is formed on the exterior of the absorber and this heated layer is pulled into a plurality of holes which are distributed over the absorber before the heat can escape by convection. These systems typically result in efficiencies of up to 75%.
In a backpass system, sunlight heats a dark surface and incoming air is heated as it is passed behind the non-perforated absorber. While inexpensive and simple to construct, backpass systems typically require that the air must travel across the back of the absorber a long distance, preferably in turbulent flow, so as to pick up as much heat as possible.
It is known that to maximize performance current systems must use a complicated arrangement of baffles or dampers within the plenum that must be carefully adjusted prior to system operation to regulate the air flow within a series of modules. Such arrangements can, however, compromise the total systems energy output.
There remains a need for an improved device which, by virtue of its design and components, would be able to overcome some of the aforementioned prior art problems.